Support conversion of clamped double values for pixel arrays in Crankshaft.

src/ia32/macro-assembler-ia32.cc

Index: src/ia32/macro-assembler-ia32.cc
diff --git a/src/ia32/macro-assembler-ia32.cc b/src/ia32/macro-assembler-ia32.cc
index d5eda7a0d7640be2bc25d2f5375316c91acdd006..5c5d15567064a1c423194696574d500d4ce86f25 100644
--- a/src/ia32/macro-assembler-ia32.cc
+++ b/src/ia32/macro-assembler-ia32.cc
@@ -77,6 +77,46 @@ void MacroAssembler::RecordWriteHelper(Register object,
 }
 
 
+void MacroAssembler::ClampDoubleToUint8(XMMRegister input_reg,
+                                        XMMRegister scratch_reg,
+                                        Register result_reg) {
+  Label above_zero;
+  Label done;
+  Label in_bounds;
+  ExternalReference zero = ExternalReference::address_of_zero();
+  movdbl(scratch_reg, Operand::StaticVariable(zero));
+  ucomisd(input_reg, scratch_reg);
+  j(above, &above_zero, Label::kNear);
+  Set(result_reg, Immediate(0));
+  jmp(&done, Label::kNear);
+  bind(&above_zero);
+  ExternalReference uint8_max_value =
+      ExternalReference::address_of_uint8_max_value();
+  movdbl(scratch_reg, Operand::StaticVariable(uint8_max_value));
+  ucomisd(input_reg, scratch_reg);
+  j(below_equal, &in_bounds, Label::kNear);
+  Set(result_reg, Immediate(255));
+  jmp(&done, Label::kNear);
+  bind(&in_bounds);
+  ExternalReference one_half =
+      ExternalReference::address_of_one_half();
+  movdbl(scratch_reg, Operand::StaticVariable(one_half));
+  addsd(scratch_reg, input_reg);
+  cvttsd2si(result_reg, Operand(scratch_reg));
+  bind(&done);
+}
+
+
+void MacroAssembler::ClampUint8(Register reg) {
+  Label done;
+  test(reg, Immediate(0xFFFFFF00));
+  j(zero, &done, Label::kNear);
+  setcc(negative, reg);  // 1 if negative, 0 if positive.
+  dec_b(reg);  // 0 if negative, 255 if positive.
+  bind(&done);
+}
+
+
 void MacroAssembler::InNewSpace(Register object,
                                 Register scratch,
                                 Condition cc,